I've owned just 2 pairs of electrostatics - Quad and Martin Logan.
A couple of years ago, I thought it time to upgrade from my 15+ year old Avantgarde Uno speakers to something more SOA. A friend I met though another forum invited me to listen to his Quad 2905 speakers and I visited expecting to hear a good sound but lacking in volume potential and a shortage of bass. I was proved very wrong on both counts. He likes to turn the volume to a level higher than I listen to and there was no shortage of bass. I was impressed enough to sniff out a used pair of 2905s that had been modified to 2912 spec by Quad, Huntingdon - mainly changing the transformers.
I knew they would not be keepers as their location in the middle of my semi-circular room would be unacceptable as these "barn doors" would obstruct my view unacceptably. However they did sound very good.
I looked around at other ELS speaker that may be more acceptable visually and, after reading reviews and auditioning in a London showroom, bought a pair of ML 13A Expressions - at double the price of new Quads. To say that I was disappointed is an understatement. They just didn’t perform and couldn't match my ancient Avantgardes for sound quality - even with Anthem room correction. They had to go, but I later established the reason they performed badly. These speakers project half their sound backwards (both the panel and the subs) so a rear wall is needed to salvage some of this sound. In my particular room this just doesn’t happen as the "rear wall" is in fact floor-to-ceiling glazing 12 ft behind one speaker and 15 ft behind the other - and at an angle. So why the ML speakers sounded so bad while the Quads sounded so good in the same location is still a mystery. Anyway, the MLs had to go. [Still for sale for any reader in UK!]
So, my old AGs sounded better than brand new MLs! What to do? I happened to notice a pair of circa 2006 Duos for sale so grabbed these at a good price and sold the Unos. Good move. A year later with a totally unjustified itch to further upgrade, I bought a pair of new Avantgarde Duo XDs - a 3 generation “upgrade”. I'm still trying to get them to perform as well as I'm sure they can, but just now they are hard pressed to convince me there's a significant improvement over my old Duos. I'll get there in the end, but Avantgarde make it difficult. The speakers are undeniably (and unnecessarily) too tall for most people's listening position unless tilted forward, and the excellent XD room correction software is totally dependent on the listeners' ears and it’s a nightmare to make the myriad of adjustments for best sound. If only they included a calibrated microphone based measuring facility so owners could see immediately where adjustments should be made, this would make a huge difference and better sounds could be easily obtained.
However, getting back to Martin Logan - if considering this brand, I'd suggest going for the hybrid range (11A, 13A, 15A etc) if you want plenty of bass. My 13As have twin 10" drivers in each speaker and the 15As have twin 12". They do need a rear wall (that's the one behind the speakers) between 2 and 6 feet behind to take advantage of the 50% sound being projected backwards. Then they will sound fantastic. The degree of detail is astonishing with no distortion or closed-in feeling one often gets from box speakers. I'd certainly have kept mine had I the right room. Most people do have the right room, but sadly mine just isn't.
Would I go for ML speakers in favour of Quad? Probably not as the Quad 2912 is £8000 and the 13A is double that price and the 15As over 3 times. The MLs look a lot better but the Quads sound amazing - and remarkably good for a full-range ELS in the bass department, though perhaps not quite up to twin 10 or 12 inch drivers offered by ML. Certainly check out the Quads if your room will take these big ugly slabs without undue complaint.
Or maybe go for these active full-range, tube-powered electrostatics. I've not yet heard them yet, but I'm hoping to when I'm next in the Netherlands! Peter